He is one of the heads of the Monster Association. He attacks Saitama but is defeated and scattered into droplets. It later reappears in a smaller form stabbing Air in the throat and being swallowed and digested by Pig God.

As a high-ranked member and a Dragon-level Mysterious Being of the Monster Association, Evil Natural Water is an extremely powerful being. As mentioned by Black Sperm (who heard it by rumour), Evil Natural Water is able to respond to other people's emotions and attack.

Homogenous body: Evil Natural Water's body is made up of water and therefore has no vulnerable internal organs or weak points to target, thus greatly reducing damage taken. Saitama's tremendously powerful punches were able to scatter him into many droplets despite this. Pig God's powerful stomach acids ended the life of the Evil Natural Water.

High-Speed Jet Streams: Evil Natural Water is capable of firing devastating high-speed jets of water in an instant. The jets of water are significantly faster than bullets, fast enough to be almost impossible to track and predict, and have a higher penetrating power.